42 RAMBLES OF A NATURALIST. 



ment correspond to more and more closely restricted 

 zoological groups. The embryo acquires first the 

 characters of the sub-division to which it belongs, 

 then successively those of the class, family, tribe, 

 genus, sub-genus, and species. Consequently two 

 embryos which could not at first be distinguished in 

 any way from one another, cease to resemble each 

 other as they continue to grow, if they belong to 

 remote groups, but they continue to be like one 

 another for a longer time, if there exist greater 

 affinities between the two species to which they 

 appertain. Both follow one common road, if we may 

 so express ourselves, until having reached a certain 

 point they take divergent paths, and each assumes 

 its own peculiar and distinctive characters. 



If these facts be true, and if the consequences that 

 we have deduced from them be correct, animals 

 belonging to one fundamental group and to one and 

 the same great sub-division of the animal kingdom 

 will continue to be like one another during a certain 

 period of their embryonic life ; subsequently they 

 will differ from one another, but they will at no 

 period assume the characters essential to one of the 

 other sub-divisions. The Articulata, for instance, 

 can never assimilate to the Mollusca, nor the Verte- 

 brata to the Radiata. The immense majority of 

 facts which have been collected in reference to this 

 subject, fully justify this conclusion. Nevertheless 

 Loven *, a naturalist of distinguished merit, de- 



* A Swedish naturalist who has published, among other works, 

 some very important researches on the development of the Cam- 

 panularias and Syncorynes, and who shares with Milne Edwards 



